The decaffeination of a vegetable material, such as aqueous coffee extract, is an important commercial process receiving much industry attention. One decaffeination approach of increasing interest is the use of caffeine adsorbents such as activated carbon or polymeric resins to adsorb caffeine from an extract. The adsorbents have not enjoyed wide acceptance though because of their tendency to adsorb large amounts of no-caffeine solids along with caffeine. In order to reduce the amount of non-caffeine solids adsorbed, the adsorbent may be treated with a mixture of carbohydrates prior to decaffeination, as is known in the art. After decaffeination of coffee extract, the adsorbent has caffeine, a small amount of non-caffeine coffee solids and carbohydrates adsorbed thereon.
Methods of recovering the adsorbed solids and caffeine are disclosed in U.S. Pat. No. 4,298,736 to Katz et al. and commonly assigned U.S. Pat. App. Ser. No. 488,354 of Katz et al. According to the Katz et al. patent, spent adsorbent is contacted with an organic acid or alcohol so that essentially all of the solids contained on the adsorbent are removed. The Katz et al. patent application describes the use of an aqueous acetic acid solution to achieve the same result. After the removal of the solids, the desorbent acid or alcohol is steam stripped and recovered from solution, leaving a caffeine-containing decaffienation process sludge. While the Katz et al. processes are effective in removing the solids and caffeine adsorbed on the adsorbent, both processes use organic acids, which acids may pose special handling problems.
It is an object of the present invention to provide a process for recovering caffeine adsorbed on activated carbon which process uses a solvent that does not pose any special handling problems.